This invention relates to a container closure of the type in which at least one flap is integrally hinged to the top panel of the closure and is adapted to be swung upwardly and downwardly to open and close a dispensing opening which is formed through the top panel. More specifically, the invention relates to a closure of the type in which means hold the flap securely in its closed position until the container is first opened and, at the same time, provide a visual indication as to whether the container has been tampered with and opened prior to purchase by the consumer. Such a closure is commonly referred to as being a tamper-evident closure.
A closure of this general type is disclosed in Foster U.S. Pat. No. 4,361,250. In that closure, plastic strips extend alongside opposite side edges of the flap and are connected to the flap by tearable webs, the strips being anchored permanently to the top panel of the closure. Before the flap is initially swung upwardly, the strips and the webs coact to hold the flap closed and to prevent accidental opening of the flap during shipment of the container. When a substantial manual lifting force is applied to the flap, the webs tear to permit the flap to separate from the rigidly anchored strips and to permit the flap to swing open. The torn web portions which remain on the strips and the side edges of the flap provide visual evidence that the container has been opened and that the original seal is no longer intact.
One of the problems with the closure disclosed in the Foster patent is that the torn webs are very small and thus only an astute observer is able to detect tampering. In addition, the unopened closure does not give the outward appearance of being a tamper-evident closure and thus a well-intentioned consumer may in good faith attempt to open the flap without realizing that he might destroy the integrity and the future saleability of the container. Moreover, the antitamper arrangement of the Foster patent does not readily lend itself to use with a closure with multiple side-by-side closure flaps.